APS semi-metallic linings are impregnated with Kevlar® fibers for optimum performance. APS metallic linings are constructed from an innovative design and from more durable materials than other brands so you get longer wear and superior stopping power for greater safety. APS discs are a good value.APS discs and linings generally cost less. When you consider the cost savings alongside the longer life, APS BlackSteel discs and linings are a value you just won't find anywhere else. APS non-metallic linings are made from a patented formula which includes Kevlar fibers. These fibers allow for maximum gripping action while maintaining the integrity of the disc and pad surfaces for longer wear.Note. Care must be taken to ensure correct bedding before use, also known as the correct brake-in procedure, conditioning or burnishing, so that peak performance can be achieved from the brake disc and linings.